TCP Monitoring

Port 514 (Syslog)

Learn about port 514 (Syslog) - security risks, vulnerabilities, and common uses. Find devices with port 514 open.

Quick Info

Port Number

514

Protocol

TCP

Service

Syslog

IANA Name

Syslog

Service Description

Network port 514 (TCP) is commonly associated with the Syslog protocol, a widely used standard for message logging. Originally designed for Unix systems, Syslog provides a mechanism for transmitting event notifications across IP networks. The protocol operates at the application layer and typically uses a client-server model. Syslog clients, such as network devices, servers, and applications, generate log messages containing information about system events, errors, and other operational data. These messages are then transmitted to a Syslog server, also known as a collector, which aggregates and stores the logs for analysis, auditing, and troubleshooting. The basic Syslog message format consists of a priority value (facility and severity) and a message payload. While traditionally using UDP on port 514, TCP is increasingly preferred for its reliability, especially in environments where message loss is unacceptable. TCP-based Syslog ensures message delivery and ordering, addressing the limitations of UDP's connectionless nature. The transition to TCP also allows for larger message sizes, accommodating more detailed event information.

## Firewall Recommendations

The decision to allow or block TCP port 514 depends on the organization's logging infrastructure and security requirements. If Syslog is used for centralized logging, the port should be open only to trusted internal networks or to external sources that are explicitly authorized to send log data. It is crucial to implement strong authentication and encryption (e.g., TLS) to protect the confidentiality and integrity of log messages. Restricting access based on source IP addresses and using firewall rules to allow only specific hosts or networks to connect to the Syslog server is recommended. If Syslog is not used or required, blocking TCP port 514 is the most secure option. Best practices include regularly patching Syslog servers to address known vulnerabilities, implementing intrusion detection systems (IDS) to monitor for suspicious activity, and conducting periodic security audits to ensure that the logging infrastructure is properly configured and secured.

Security Information

Syslog, particularly when running over TCP port 514 without proper security measures, presents several security risks. The primary concern is the potential for unauthorized access to sensitive log data. If the communication channel is not encrypted (e.g., using TLS), attackers can eavesdrop on the network traffic and intercept log messages containing confidential information such as usernames, passwords, and system configurations. Furthermore, attackers could potentially inject malicious log entries to mask their activities, disrupt security investigations, or even manipulate system behavior if the log data is used for automated decision-making. Another risk stems from buffer overflow vulnerabilities in older Syslog implementations, which could be exploited to gain control of the server. Finally, if the Syslog server is not adequately secured, it could become a target for denial-of-service (DoS) attacks, rendering it unable to collect and process log data, thereby hindering security monitoring and incident response efforts. Because logs often contain sensitive operational data, attackers frequently target syslog servers to gain insights into network infrastructure, application vulnerabilities, and user behavior, all of which can be leveraged for further attacks.

Known Vulnerabilities

CVE	Name	Severity	Description
CVE-2019-14907	rsyslog Remote Code Execution	Critical	A heap-based buffer overflow vulnerability exists in rsyslog versions before 8.19.08 due to improper validation of the length of data received from a client, potentially leading to remote code execution.
CVE-2017-6519	syslog-ng Heap Buffer Overflow	High	A heap-based buffer overflow vulnerability exists in syslog-ng versions before 3.9, potentially leading to denial of service or arbitrary code execution.
CVE-2008-0565	syslogd format string vulnerability	High	A format string vulnerability in syslogd allows remote attackers to execute arbitrary code via format string specifiers in a log message.
CVE-2023-27953	rsyslog vulnerability	Medium	An input validation issue was discovered in rsyslog. This could potentially allow a malicious actor to cause a denial of service condition.
CVE-2023-36838	syslog-ng vulnerability	High	A vulnerability was found in syslog-ng. This issue occurs when handling incoming messages from a TCP source that uses the IETF-syslog protocol. By sending a crafted message, a malicious user can cause a crash of syslog-ng.

Malware Associations

While no specific malware is definitively known to *exclusively* use port 514/TCP, some botnets and malware families may leverage Syslog as a communication channel for command and control or data exfiltration, especially when targeting vulnerable or misconfigured systems. Generic trojans might use it for stealthy logging and information gathering.